In a manufacturing system for the production of paper products such as paper towels, a log of rolled, non-woven, fibrous paper web product is produced and eventually cut into consumer-size rolls for packaging. Various characteristics of the log are critical to the operation of downstream packaging equipment. For example, if the diameter of the log becomes too large, the excessive diameter can cause the packaging equipment to operate inefficiently and possibly malfunction. On the other hand, if the diameter of the finished product is too small, it may adversely affect a consumer's perception of quality and value of the final product, thus negatively impacting sales of the product.
Log diameter is presently measured manually by an operator in which the operator checks the diameter at defined time intervals. If the operator's manual measurements indicate that the diameter falls outside of a desired range, the operator manually adjusts appropriate portions of the manufacturing equipment to increase or decrease the diameter as required.
By way of example, the operator can measure the log manually using wheels and skids, which contact the log to take diameter, firmness and other log measurements. Based on these measurements, the operator makes appropriate adjustments in the manufacturing process to alter the log diameter. Unfortunately, some system adjustments require starting and stopping the system while incremental adjustments and measurements are conducted until the operator determines that the log diameter is within tolerance.
The variation in the process means that single measurements are not necessarily characteristic of the actual diameter average, and since these process variables can not be completely controlled, non-uniform finished rolls, which are undesirable both to the manufacturer and to the consumer, are typically produced.
Various approaches to measure the log diameter without physical contact or operator intervention have been attempted. One approach incorporates a number of lasers to triangulate the log diameter using a plurality of laser beams, which are specifically directed at the log to measure distances from a surface of the log. These laser beams typically penetrate the log at least slightly and produce inaccurate measurements. Moreover, installation and calibration of the triangulating lasers tend to be more complicated and time consuming than desired.